Made for your head, not for paper
The column method we learnt at school is built for a pencil. These techniques work from the left, round to friendly numbers and keep one running total, which is how calculating without paper actually goes.
30-day mental arithmetic program
Do everyday sums in your head, one shortcut a day
The Mental Math Protocol teaches one calculation technique a day for 30 days, from adding left to right to splitting a bill and working out a discount.
Each day brings a short lesson, two worked examples shown step by step and a timed drill of fresh problems, with your personal bests kept for you.
- Online access once payment is confirmed
- Works in your browser
- In 5 languages
Mental MathDay 9 of 30
×11
- 1Learn
- 2Drill
- 3Review
- 4Done
78 × 11
858
The shortcut
Split the digits and put their sum in the middle.
52 × 11 → 5 | 5 + 2 | 2 = 572
- 30daily lessons, one calculation technique each
- 60worked examples you reveal step by step
- 40everyday word problems in 4 topics
- 3levels for every technique, with new problems each time
Why a protocol
The methods people use for sums in their head, set out one at a time
About ten minutes a day
A lesson of about 120 words, two worked examples, a drill of 10 problems and a short mixed review. Small enough to fit before work or after dinner.
Practice that keeps coming
Drill problems are generated for each technique at three levels, so a repeat never shows you the same list. A wrong answer shows the right one and the shortcut beside it.
Numbers from real life
Percentages, clock times, unit prices, shared bills, tips and discounts all have their own day, and 40 word problems put them in everyday situations.
What is in the app
Everything for the daily routine, and for the days after it
Today
Your day of the 30, a short line on what it covers, the 10-minute warm-up, a word problem of the day and your week in three numbers.
The 30 days
Five parts of six days, from foundations to everyday numbers. Each day goes Learn, Drill, Review, Done. Nothing is locked, so you can open any day.
Lesson and worked examples
A clear explanation of the technique, its shortcut in one line, and two worked examples you reveal one step at a time.
Timed drill
10 problems for the day's technique at level 1, 2 or 3. The clock runs while you answer and stops while you read a correction.
Mixed review
From day 2, six problems from earlier days follow the drill, without a clock, so the older techniques keep turning up.
Free Practice
Pick any techniques and a level, then choose a 60-second sprint, 20 problems against the clock or an untimed set.
Word Problems
40 situations about shopping, recipes, travel and sharing, each with a worked explanation. Money can show plain numbers or a currency symbol of your choice.
Records
Personal bests by technique, level and mode, accuracy, days completed and a practice calendar of the last five weeks.
Cheat Sheet
All 30 shortcuts on one printable page, each with a short example.
Numbers follow your language: a decimal point in English, a decimal comma in French, Spanish, Italian and German. You can type answers with either, on the built-in number pad or your own keyboard.
Try a drill
Day 9 of the protocol, as it works in the app
Read the shortcut, step through the worked example, then answer five problems. The text is the app's own.
Day 9 of 30
×11
Multiplying a two-digit number by 11 has a pretty pattern. Write the two digits apart and put their sum in the middle: for 52 × 11, the digits 5 and 2 with 5 + 2 = 7 between them give 572.
The shortcut
Split the digits and put their sum in the middle.
Worked example 2
87 × 11
- Outer digits: 8 … 7
- Middle: 8 + 7 = 15, write 5 and carry 1
- 8 + 1 = 9, so 957
Answer: 957
- 52 × 11
- 34 × 11
- 63 × 11
- 78 × 11
- 45 × 11
52 × 11
Correct
Type a number first.
Not quite
The answer is
Shortcut: Split the digits and put their sum in the middle.
Set finished
0 right out of 5
In the app, the drill has 10 problems at the level you choose, and a new personal best is kept for each level.
How it works
From payment to your first drill
- 1
Choose and pay
Choose your currency in the offer below and pay on the secure payment page.
- 2
Access opens
Your online access opens once payment is confirmed.
- 3
Open it in your browser
Use it on your phone, tablet or computer. There is nothing to install.
- 4
Start day 1
Set up your personal space in under a minute, and day 1, adding left to right, is waiting on Today.
The 30 days
Five parts, six days each, every technique with its own drill
Each day has a lesson of about 120 words, a one-line shortcut, 2 worked examples and problems at 3 levels. Here are all 30, part by part.
Days 1 to 6
Foundations
- Adding left to right
- Making tens
- Complements to 100 and 1,000
- Subtracting by adding up
Also: doubling and halving, ×4 and ×8.
Days 7 to 12
Quick multiplications
- ×5 and ÷5
- ×9
- ×11
- ×25
Also: multiplying by 10, 100, 1,000 and decimals; two-digit × one-digit.
Days 13 to 18
Bigger products
- Squares ending in 5
- Squares near 50
- Multiplying near 100
- Two-digit × two-digit: the cross method
Also: breaking numbers apart, difference of squares.
Days 19 to 24
Division, checks and percentages
- Divisibility checks
- Checking with digit sums
- Percentages: 10%, 5% and 1%
- Percentage increase and decrease
Also: dividing by 2, 4 and 8; percentages of anything.
Days 25 to 30
Everyday numbers
- Estimating and rounding
- Time arithmetic: hours and minutes
- Unit price comparison
- Tips and discounts
Also: fractions and percentages, splitting a bill.
40 word problems
Everyday situations
- 10 about shopping
- 10 about recipes
- 10 about travel and time
- 10 about sharing
Each one links to the day whose technique it uses.
Included bonuses
Three extras for paper and for busy mornings
Printable
The cheat sheet
All 30 shortcuts on one page, grouped by part, each with its one-line rule and a short example. Print it or save it as a PDF.
97 × 94 → 91 | 18 = 9,118
Routine
The 10-minute warm-up
Five blocks of 2 minutes: bonds and complements, doubles and halves, quick multiplications, percentages and a mixed bag. Your warm-ups are listed in the app, and the routine prints on one page.
5 × 2 min
Printable
Practice worksheets
From Free Practice, print 20 problems from the techniques and level you chose, with the answers at the end. Handy for a train journey or for homework help.
20 problems + answers
Who it is for
For adults who want sums to feel manageable
- People who reach for a phone to split a bill or check a discount, and would like another option.
- Parents who want clear methods to show when helping with homework.
- Anyone whose work involves quick percentages, estimates or timings.
- People who simply enjoy numbers and want a structured daily routine.
What it is not
- It is not a school course or an exam preparation program.
- It is not a calculator: you do the arithmetic, the app sets the problems and checks the answers.
- It does not promise how quickly or how well you will calculate. You practise, and the app keeps your records.
Educational content. Our products teach practical techniques and offer general information and tools. They are not medical, psychological, nutritional, legal or financial advice and do not promise any particular result. For advice about your own circumstances, consult a qualified professional.
Access and billing
The plain facts
The price, in US dollars or euros, is shown in the offer below.
- Delivery
- All our products are digital and nothing is sent by post. Access is online and opens as soon as your payment is confirmed.
- Access period
- One payment gives you 12 months of online access from the date of purchase. It is not a subscription, so nothing renews.
- Devices
- A web app for current versions of Chrome, Safari, Firefox and Edge, on phones, tablets and computers. Nothing to install. An internet connection is needed.
- Languages
- The app and its content are available in English, French, Spanish, Italian and German. You can switch language at any time in Settings.
- Ending the contract
- Nothing renews, so there is no subscription to stop. To end the contract early, use our “Cancel contracts here” page or write to support. See our Cancellation Policy.
- Refunds
- For 7 days after the charge, you may ask us to refund it in full. See our Refund Policy.
- Right of withdrawal
- This is an online service supplied over time. Consumers in the European Union or the European Economic Area can withdraw within 14 days. If you asked for an immediate start and then withdraw, you pay only for the service supplied until then. See our Right of Withdrawal.
- Conformity
- The legal guarantee of conformity for digital content and digital services applies to this product.
One payment, 12 months of access
The Mental Math Protocol
One calculation shortcut a day for 30 days, with worked examples, timed drills and your own records.
- 30 daily lessons with 60 worked examples
- A timed drill and a mixed review every day
- Free Practice: sprint, 20 problems or untimed, at 3 levels
- 40 word problems with worked explanations
- Records of your personal bests and practice days
- The cheat sheet, the 10-minute warm-up and printable worksheets
- In English, French, Spanish, Italian and German
USD 39.00 one-time, 12 months of access
EUR 59.00 one-time, 12 months of access
How the purchase works
A single payment of USD 39.00 gives you 12 months of online access from the date of purchase. It is not a subscription: nothing renews and nothing else is charged.
A single payment of EUR 59.00 gives you 12 months of online access from the date of purchase. It is not a subscription: nothing renews and nothing else is charged.
For consumers in the European Union, the price already includes any VAT that applies. Paying by card costs nothing extra.
For 7 days after any charge, you may ask us to refund that charge in full (Refund Policy). This voluntary policy sits alongside your statutory rights and never limits them. Consumers in the European Union or the European Economic Area also have a statutory 14-day right of withdrawal.
Seller: Bidcrest Group LLC, 8200 NW 41st Street, 2nd Floor, Doral, FL 33166, United States · support@bidcrestgroup.com. Bidcrest Group LLC is responsible for this order, its delivery and customer support. You pay on a secure page run by our third-party payment processor.
We take the major credit and debit cards, including Visa and Mastercard. The payment page shows which methods you can use for your order before you confirm it. This product is supplied online only and is not offered in countries or regions under comprehensive sanctions or in the other cases set out in our Terms of Service.
Your purchase gives you a personal licence to use the product online during the access period. The licence cannot be transferred and does not make you the owner of the product. Details: Terms of Service.
Designed and operated by Bidcrest Group LLC
Bidcrest Group LLC is a Wyoming limited liability company with its principal office in Doral, Florida, United States.
Write to support@bidcrestgroup.com with any question about your order or your access. Our support team replies within 48 business hours, Monday to Friday.
Company details are in our Legal Notice.
Questions
Good to know before you start
What exactly do I get?
A web app with 30 daily lessons, each with a one-line shortcut, 2 worked examples, a timed drill of 10 generated problems at 3 levels and, from day 2, a mixed review of earlier days. You also get Free Practice with three modes, 40 word problems with worked explanations, Records of your personal bests and practice days, the printable cheat sheet, the 10-minute warm-up and printable practice worksheets.
Do I need to be good at maths already?
No. Day 1 starts with adding two-digit numbers, and every technique has a level 1 with smaller numbers so you can learn the moves before the numbers grow.
How much time does it take?
A day takes about 10 minutes: the lesson, the two worked examples, the drill and the review. Nothing is locked, so you can move on sooner or take a day more whenever you like.
What devices and browsers do I need?
It works in current versions of Chrome, Safari, Firefox and Edge on phones, tablets and computers. Nothing needs to be installed, and an internet connection is required.
Which languages is it in?
The app and its content are available in English, French, Spanish, Italian and German. You can switch language at any time in Settings.
Can I pay in euros or US dollars?
Yes. Choose the currency in the offer above before you continue to the payment page. The product and the access are the same in either currency. If your card is in another currency, your bank may add its own conversion fee.
How do I get access?
All our products are digital and nothing is sent by post. Access is online and opens as soon as your payment is confirmed.
Is my progress saved?
Yes. Your days, drills, personal bests and word problems are saved automatically in your personal space. Details are in our Privacy Policy.
How does billing work?
You pay once. That payment gives you 12 months of online access from the date of purchase. It is not a subscription: nothing renews and nothing else is charged.
How do I cancel?
You can cancel whenever you like on our cancellation page (“Cancel contracts here”, linked in the footer of every page) or by emailing support@bidcrestgroup.com, preferably from the address used at checkout. You don't have to explain why, and any clear request to cancel is accepted.
How do refunds and withdrawal work?
Our 7-day refund policy: for 7 days after any charge, you may ask us to refund that charge in full, even if you have started using the product. This is a voluntary extra that sits alongside your statutory rights, including any statutory right of withdrawal, and never limits them.
If you are a consumer in the European Union or the European Economic Area, the law gives you 14 days from the conclusion of your contract to withdraw from it, without stating a reason. Those 14 days run from your first purchase; a renewal does not restart them. You can withdraw on our withdrawal page (“Withdraw from contract here”, linked in the footer of every page) or by emailing support@bidcrestgroup.com.
How will the charge appear on my bank statement?
Charges from us show on your bank or card statement with a descriptor that includes "BIDCREST". The rest of the wording can change with the product and the bank.
Can I print?
Yes. You can print the cheat sheet with all 30 shortcuts, the 10-minute warm-up routine and practice worksheets of 20 problems with answers, or save them as PDF from the print window.
Is this medical or psychological advice?
No. Educational content. Our products teach practical techniques and offer general information and tools. They are not medical, psychological, nutritional, legal or financial advice and do not promise any particular result. For advice about your own circumstances, consult a qualified professional.
How do I contact support?
Write to support@bidcrestgroup.com. Our support team replies within 48 business hours, Monday to Friday.
What if I can't find my access?
Can't find your access, or the product won't load? Email support@bidcrestgroup.com. We will get your access working again or, if we cannot, cancel the order and refund it.